The present invention generally relates to motor control circuitry and, more particularly, the present invention relates to fan motor control circuitry used in a HVAC system that allows fan motor speed operation to be performed at two separate locations.
With the introduction of the minivan and sport utility vehicle (SUV), rear HVAC controls have become a popular feature. These rear controls allow the vehicle""s rear occupants to control the temperature and airflow in the rear of the vehicle, independent from the front HVAC settings. Additionally, an override circuit usually exists to allow the rear HVAC to be controlled from the front seat and provides the ability to disable operation of the rear control panel from the front seat.
In recent years, additional features have been added to vehicles for the benefit of rear occupants. More specifically, rear entertainment systems are now offered that allow passengers behind the front seat to control and enjoy music and videos. The addition of these rear entertainment systems as well as the controller has enlarged and/or increased the number control assemblies required in the rear of the vehicle. As a result of these additional rear seat components, the controls, often positioned overhead in the vehicle compartment, have considerably grown in size.
The related art utilizes mechanical switches in the rear passenger area to control the rear HVAC system. Switches controlling low fan speeds are capable of handling the full current load, as required by the fan motor, for all speeds selected. Alternatively, low current switches for high fan speeds activate relays or similar high current switching devices near the fan motor in a more distributed control system.
Distributed systems have used PWM (pulse width modulation) control for the control of the fan motor. Distributed systems are employed in PWM controls to avoid high EMI generated over the long wires that connect the control panel directly to the fan motor. However, such systems have a cost disadvantage by virtue of having two control assemblies, one for PWM switching the fan motor current and another for remotely controlling the PWM circuit. The present invention was developed in light of these and other drawbacks.
In light of these and other drawbacks, the present invention replaces the rear fan control mechanical switch with an electronic circuit that provides improved integration into the rear seat entertainment system.
In one aspect of the present invention, a fan control includes a front fan switch, rear fan switch, rear fan control circuit, controller and fan motor. The front fan switch and the rear fan switch are electrically connected to the controller. Likewise, the rear fan control circuit is also electrically connected to the controller. The fan motor is electronically connected to the rear fan control circuit and the front fan switch. According to this design, the controller is responsive to inputs from the rear fan switch to adjust the fan speed of the fan motor when the front fan switch provides a logical ON signal to the controller. By this means, a front seat operator is able to shift operational control to the rear seat and to disable the rear seat control.
In another aspect of the present invention, a vehicle is provided having the fan control as described above according to the present invention. Specifically, the fan control includes a front fan switch, rear fan switch, controller, rear fan control circuit and a fan motor. The front fan switch is positioned in the front seat area of the vehicle, while the rear fan switch is positioned in the rear seat area of the vehicle. Accordingly, the rear fan switch can be incorporated into an entertainment panel of an entertainment system located in the rear seat area of the vehicle.